The present invention relates to a TV video data input apparatus employed for processing TV pictures by means of a computer.
It is a general practice that the video data from a TV camera are sampled and quantized, and the quantized data are fed into a computer to effect a picture processing.
For feeding the quantized data into a computer that effects a picture processing, such an input apparatus has been conventionally employed as having the following arrangement: A video signal from a TV camera is first converted into digital data by an A/D converter and written in a video memory. In this case, the addresses of the digital data are specified by an address generator. The sampling order on a TV screen is as follows: Assuming that sampling points (picture elements) on a first horizontal scanning line are denoted by (1, 1) to (m, 1), those on a second horizontal scanning line by (1, 2) to (m, 2), and those on an n-th scanning line by (1, n) to (m, n), during a first horizontal scanning, sampling is effected over the sampling points, from (1, 1) to (2, 1), (3, 1), . . . (m, 1), and during a subsequent horizontal scanning, sampling is effected over the sampling points (1, 2), 2, 2), . . . (m, 2). Then, in a similar manner, sampling is continued up to the sampling point (m, n). Thus, the video data about all the picture elements on one frame are written in the memory during one vertical scanning.
When the video data about all the picture elements on one frame are thus sampled during one vertical scanning period, a high-speed memory is required. As a high-speed memory for this purpose, a static RAM is available which is short in access time. This RAM is, however, high in cost and poor in mounting properties disadvantageously.
As another prior art, there is an input apparatus which employs such a means that video data about all the picture elements on one frame are written in a memory during the period of several vertical scannings in the case where a real-time data processing is not required, i.e., it is not necessary to write in the memory all the video data on one frame during one vertical scanning period, e.g., in the case of a static picture or the like. In this prior art, as the memory, it is possible to employ a dynamic RAM which is long in access time and more excellent in mounting properties as well as cost than the static RAM.
However, this method in which all the picture element data on one frame are sampled by several vertical scannings is unfavorably low in sampling rate, so that any dynamic picture cannot be handled disadvantageously.
In addition, since the conventional means of sampling all the picture element data during one vertical scanning period and the other conventional means of sampling all the picture element data during the period of several vertical scannings are independent of each other and different in hardware from each other, the kinds of memory devices usable for the respective means are limited. Accordingly, it has been impossible to make a single data input apparatus effect both the writing of all the picture element data in real time and the writing of the all the picture element data during the period of several vertical scannings.